The lock assembly to be described has particular, although not exclusive, utility in hotels and motels, where, for security purposes, it is often desirable to change the locks in the doors of the rooms from time to time. The lock assembly is of the same general type as described and claimed in Copending Applications Ser. No. 455,576, filed Mar. 28, 1974, in the name of James A. Millett; Ser. No. 443,310, filed Feb. 19, 1974, in the names of James W. Raymond and James A. Millett; and Ser. No. 438,867, filed Feb. 1, 1974, in the name of James W. Raymond.
The lock assembly of the invention, in the embodiment to be described, includes three replaceable logic ring members, as explained briefly above, namely a guest logic ring, a maid logic ring, and a master-emergency logic ring. As also pointed out, the guest logic rings, which are preferably different for each lock in the establishment, are operated by the keys issued to the guests; the maid logic rings, which are preferably the same for a group of locks in the establishment, are operated by keys to the maids; and the master-emergency logic rings, which are preferably the same for all the locks in the establishment, are operated by keys issued to the technicians and maintenance men of the establishment.
None of the keys mentioned above can unlock the door of any room in the establishment, if the door is bolted by the usual dead bolt mechanism, so that the security and privacy of the guests may be assured. However, a further key, termed an emergency key, is also provided. The emergency key is similar in most respects to the master key, and it operates in conjunction with the master logic ring. However, the emergency key has an additional feature, as noted above, of being able to unlock the lock even if the door is bolted by the usual dead bolt, so that access to a room under any conditions may be achieved. Also, the emergency key has the ability of setting the lock to a release position, in which the various logic rings can be removed and replaced.